Unique responses of Helicobacter pylori to exogenous hydrophobic compounds

Targeted nanotherapeutics for the treatment of Helicobacter pylori infection

Helicobacter pylori infection is involved in gastric diseases such as peptic ulcer and adenocarcinoma. Approved antibiotherapies still fail in 10 to 40% of the infected patients and, in this scenario, targeted nanotherapeutics emerged as powerful allies for H. pylori eradication. Nano/microparticles conjugated with H. pylori binding molecules were developed to eliminate H. pylori by either (i) blocking essential mechanisms of infection, such as adhesion to gastric mucosa or (ii) binding and killing H. pylori through the release of drugs within the bacteria or at the site of infection. Glycan antigens (as Lewis B and sialyl-Lewis X), pectins, lectins, phosphatidylethanolamine and epithelial cell membranes were conjugated with nano/microparticles to successfully block H. pylori adhesion. Urea-coated nanoparticles were used to improve drug delivery inside bacteria through H. pylori UreI channel. Moreover, nanoparticles coated with antibodies against H. pylori and loaded with sono/photosensitizers, were promising for their application as targeted sono/photodynamic therapies. Further, non-specific H. pylori nano/microparticles, but only active in the acidic gastric environment, coated with binders to bacterial membrane, extracellular polymeric substances or to high temperature requirement A protease, were evaluated. In this review, an overview of the existing nanotherapeutics targeting H. pylori will be given and their rational, potential to counteract infection, as well as level of development will be presented and discussed.

Characterization, mechanism and in vivo validation of Helicobacter pylori antagonism by probiotics screened from infants' feces and oral cavity

Helicobacter pylori (H. pylori) infection is a major cause of chronic gastritis, intestinal metaplasia, and gastric carcinoma. Antibiotics, the conventional regimen for eliminating H. pylori, cause severe bacterial resistance, gut dysbiosis and hepatic insufficiency. Here, fifty lactic acid bacteria (LAB) were initially screened out of 266 strains obtained from infants' feces and oral cavity. The antagonistic properties of these 50 strains against H. pylori were investigated. Based on eight metrics combined with principal component analysis, three LAB with probiotic function and excellent anti-H. pylori capacity were affirmed. Combining dynamics test, metabolite assays, adhesion assays, co-cultivation experiments, and SEM and TEM observations, LAB were found to antagonize H. pylori by causing coccoid conversion and intercellular adhesion. Furthermore, it was found that LAB antagonized H. pylori by four pathways, i.e., production of anti-H. pylori substances, inhibition of H. pylori colonization, enhancement of the gastric mucosal barrier, and anti-inflammatory effect. In addition, animal model experiments verified that the final screened superior strain L. salivarius NCUH062003 had anti-H. pylori activity in vivo. LAB also reduced IL-8 secretion, ultimately alleviating the inflammatory response of gastric mucosa. Whole genome sequencing (WGS) data showed that the NCUH062003 genome contained the secondary metabolite biosynthesis gene cluster T3PKS. Furthermore, NCUH062003 had a strong energy metabolism and substance transport capacity, and produced a small molecule heat stable peptide (SHSP, 4.1-6.5 kDa). Meanwhile, LAB proved to be safe through antibiotic susceptibility testing and CARD database comparisons.

Molecular mechanism of calcitriol enhances membrane water permeability

Helicobacter pylori (H. pylori) exhibits a unique membrane lipid composition, including dimyristoyl phosphatidylethanolamine (DMPE) and cholesterol, unlike other Gram-negative bacteria. Calcitriol has antimicrobial activity against H. pylori, but cholesterol enhances antibiotics resistance in H. pylori. This study explored the changes in membrane structure and the molecular mechanisms of cholesterol/calcitriol translocation using well-tempered metadynamics (WT-MetaD) simulations and microsecond conventional molecular dynamics (CMD) simulations. Calcitriol facilitated water transport across the membrane, while cholesterol had the opposite effect. The differing effects might result from the tail 25-hydroxyl group and a wider range of orientations of calcitriol in the DMPE/dimyristoyl phosphatidylglycerol (DMPG) (3:1) membrane. Calcitriol moves across the bilayer center without changing its orientation along the membrane Z-axis, becomes parallel to the membrane surface at the membrane-water interface, and then rotates approximately 90° in this interface. The translocation mechanism of calcitriol is quite different from the flip-flop of cholesterol. Moreover, calcitriol crossed from one layer to another more easily than cholesterol, causing successive perturbations to the hydrophobic core and increasing water permeation. These results improve our understanding of the relationship between cholesterol/calcitriol concentrations and the lipid bilayer structure and the role of lipid composition in water permeation.

Aspects for development of novel antibacterial medicines using a vitamin D3 decomposition product in Helicobacter pylori infection

A previous study by our group demonstrated that a vitamin D3 decomposition product (VDP1) acts as the selective bactericidal substance on Helicobacter pylori. VDP1 is an indene compound modified with a carbonyl and an alkyl. The alkyl of VDP1 turned out to be a mandatory structure to exert effective bactericidal action on H. pylori. Meanwhile, it still remains to be clarified as to how influence the alteration of the carbonyl in VDP1 has on the anti-H. pylori activity. In this study, we synthesized novel VDP1 derivatives that replaced the carbonyl of VDP1 by various functional groups and investigated the antibacterial action of the VDP1 derivatives on H. pylori. VDP1 derivatives retaining either a hydroxy (VD3-1) or an acetic ester (VD3-3) exhibited more effective bactericidal action to H. pylori than VDP1. The replacement of the carbonyl of VDP1 by either an allyl acetate (VD3-2) or an acrylic acid (VD3-5) provided almost no change to the anti-H. pylori activity. Apart from this, an isomer of VDP1 (VD3-4) slightly improved anti-H. pylori activity of VDP1. Meanwhile, the replacement of the carbonyl of VDP1 by a methyl acrylate (VD3-6) attenuated the anti-H. pylori activity. As with VDP1, its derivatives also were suggested to exert the anti-H. pylori action through the interaction with myristic acid side chains of dimyristoyl-phosphatidylethanolamine, a characteristic membrane lipid constituent of this pathogen. These results indicate that it is capable of developing specific antibacterial medicines for H. pylori targeting the biomembranal dimyristoyl-phosphatidylethanolamine using VDP1 as the fundamental structure.

Vitamin D and Its Association with H. pylori Prevalence and Eradication: A Comprehensive Review

Taking into account previous data that sustain a relationship between vitamin D deficiency and higher H. pylori infection positivity rates, this review aims to assess the influence of vitamin D deficiency and/or insufficiency upon the prevalence of H. pylori infection and its eradication success. Three major databases were searched for articles that analyzed a relationship between vitamin D status and H. pylori infection. The literature search retrieved a total of 37 reports, after the article selection process. Hypovitaminosis D emerged as a potential risk factor for H. pylori infection, given the higher prevalence of vitamin D deficiency and/or insufficiency among H. pylori-positive subjects. Furthermore, the same type of micronutrient deficiency has been directly linked to H. pylori eradication failure. An inverse linear relationship between vitamin D status and gastric cancer risk exists, but the additional involvement of H. pylori in this correlation is still in question. The potential benefit of oral supplements in enhancing the success of classical therapeutic regimens of H. pylori still requires future research. Future population-based studies from larger geographical areas are warranted to address this subject in more depth.

A novel role of catalase in cholesterol uptake of Helicobacter pylori

Helicobacter pylori infection is known to be a significant risk factor for the development of gastric cancers in humans. This pathogen exhibits unique biological characteristics in membrane lipid composition. Specifically, H. pylori incorporates exogenous cholesterol into biomembranes and uses cholesterol as the membrane lipid constituents. A previous study by our group demonstrated that phosphatidylethanolamine of H. pylori functions as the cholesterol-binding lipid. It is, however, unclear whether H. pylori is equipped with protein molecules involved in the cholesterol uptake. We, therefore, examined H. pylori proteins that tightly bind to cholesterol. As a consequence, H. pylori catalase (KatA) turned out to be a candidate of the cholesterol uptake-associated protein. In addition, an H. pylori mutant strain that expresses KatA protein lacking catalase activity was significantly lower in total cholesterol contents than the wild-type H. pylori strain. The putative amino acid sequence of KatA found out to contain a number of the cholesterol recognition/interaction amino acid consensus sequence domains (CRAC and CARC domains). These results suggest that H. pylori KatA with normal folding conformation acts as the cholesterol-binding or -storage protein.

A short review, effect of dimethyl-β-cyclodextrin on the interaction between Helicobacter pylori and steroidal compounds

The 2,6-di-O-methyl-β-cyclodextrin (dMβCD) is an amphiphilic annular compound consisting of seven dimethyl-glucose molecules. This compound is well known as a solubilizer of lipophilic compounds. Especially, dMβCD extracts cholesterol from the plasma membrane of mammalian cells and releases the cholesterol to the aqueous solution. The experimental use of dMβCD, therefore, serves to investigate the role of cholesterol in the mammalian cell membrane. It is, however, unclear as to how dMβCD extracts cholesterol incorporated into the glycerophospholipid biomembrane. Meanwhile, dMβCD acts as a beneficial compound for Helicobacter pylori and is used as the standard component for supporting the growth of this bacterium in the serum-free culture. However, the detailed mechanism of dMβCD for supporting the growth of H. pylori is still to be clarified. H. pylori is a Gram-negative microaerophilic bacillus recognized as a pathogen concerned with gastrointestinal diseases in human. Previous studies by our group have successfully obtained the H. pylori strains culturable without dMβCD and demonstrated the distinct effects of dMβCD on the interaction between H. pylori and exogenous steroidal compounds. For instance, dMβCD promotes and inhibits the absorption of cholesterol and several steroidal compounds respectively into the biomembranes of H. pylori. In this study we summarized behaviors of dMβCD toward steroidal compounds relevant to H. pylori.

The Association between Serum Vitamin D Levels and Helicobacter pylori Presence and Eradication

Background: The success of Helicobacter pylori (H. pylori) eradication depends on several host and treatment factors. Serum vitamin D levels may be associated with H. pylori infection and eradication rates. We investigated the association between vitamin D and H. pylori infection and eradication, using a large electronic database based on medical records from a population-based health maintenance organization. Methods: Data regarding adults who underwent H. pylori testing and had vitamin D measurements within one month of H. pylori testing were collected. H. pylori infection was ascertained using urea breath or stool antigen tests. A negative H. pylori test following a positive result implied eradication. Multivariate regression models were constructed to assess associations between H. pylori infection, eradication, and vitamin D. Results: Among 150,483 members who underwent H. pylori testing from 2009 to 2018, 27,077 (18%) had vitamin D measurements. Vitamin D levels were inversely associated with H. pylori infection, p < 0.001. The odds of a positive H. pylori test were 31% higher among patients with vitamin D levels <20 ng/mL, compared with those with levels ≥20 ng/mL (OR 1.31, 99% CI 1.22–1.4, p < 0.001). Purchase of vitamin D supplements was associated with a negative subsequent H. pylori test (p < 0.001). Mean vitamin D levels were moderately higher in those with successful vs. failed H. pylori eradication (19.34 ± 9.55 vs. 18.64 ± 9.61, p < 0.001). Conclusions: Vitamin D levels are associated with H. pylori infection. Increased vitamin D levels are associated with successful H. pylori eradication. Vitamin D may have a role in H. pylori eradication.